The term prescribed burning refers to a management practice in which fire is used to burn a predetermined area under specified environmental conditions. Burning in this case is used as a management tool in areas that are vulnerable to catching fire due to the ground cover that acts as fuel load. In addition, burning is considered to be the most environmentally friendly and cheapest method of having woody growth in an ecosystem controlled. Prescribed burning in the United States is common.
In this form of burning, controlled fires are used to burn a specified land area after proper planning which ensures that the present weather conditions are favorable for the burning. When weather conditions are not suitable for the burn, negative impact of the fire in the burnt areas is likely to be witnessed (Dale et al, 2009). In the United States, prescribed burning is considered to be a very important management tool due to the benefits associated with it. Both the landowners and the United States National Forest System have been using prescribed burning for many years.
According to the United States fire policy in relation to the forest ecosystem, there is need to undertake prescribed burning in order to enhance the growth of commercial forests, prevent wildfire damage and to enhance fire dependent ecosystems. However, prescribed burning has been criticized for its negative impact on the environment.
For instance, prescribed burning results to the clearing of land or use of land for agricultural activities that have negative effects on the environment. In this paper, the impact of prescribed burning on the environment in the United States will be discussed. The paper will focus on the effect of prescribed burning on land after it is cleared by prescribed fires. Land clearing that results from the burning impacts negatively on the vegetation, soil, water and biodiversity.
In the United States prescribed burning is made necessary by the conditions in the forest ecosystems or ranches. The burning aims at preventing wildfires that can damage properly or lead to death of the people if the fuel load on the ground encourages wild fires. In addition, the United States national forest system undertakes prescribed burning activities due to the ecological benefits that burning gives to the forests. The national forest system associates prescribed burning to the reduction of wildfire hazards, land improvement, game habitat enhancement, insect and disease management and site preparation for reforestation (Biswell, 1999).
Examples of areas that have undergone prescribed burning activities include the California wild lands, Florida Flatwoods and the Southern eastern US National Forest. It is important to realize that although prescribed burning in these areas has its benefits to the ecosystem and the people; it also impacts negatively on the environment over time.
Negative environmental impact of prescribed burning occurs despite the fact that prescribed burning is planned in a manner that minimizes negative effects of burning on the environment. This has made the issue of prescribed burning to become a subject of debate in the country .While some consider prescribed burning to reduce negative impact of wild fires on the environment, burning can also impact negatively on the environment. Land clearing that result from the burning has negative effect on the environment.
Negative impact of Prescribed burning on vegetation after clearing of land
Prescribed burning results to the clearing of land in a predetermined area as the fire burns the fuel load. The burning has both indirect and direct negative effects after land clearing by the fire. Land clearing in turn has negative effects on the vegetation, water, soil and wildlife. The negative impact of prescribed burning in the United States has been witnessed in some areas because prescribed burning has become a very important activity in the country. Every year, hundreds of thousands of hectares are burned.
Although various methods of burning are used burn the vegetation cover in the predetermined areas, fires destroy the existing vegetation by either injuring or killing the entire plant or parts of the plant. This depends on the duration that the fire burns or the intensity of the fire. Prescribed burning based on the slash reduction method results to the reduction of debris.
This method is also used to reduce debris in case of a natural event or road construction. When management ignited fire is used, the burning of a stand that has been established is done while ensuring that fire does not spread beyond the predetermined area. While small trees are completely burned during the burning, larger trees may survive the fires but some of their trees may be destroyed. When fires are ignited, the burning forest fuels increase the temperatures which make it difficult for the vegetation to survive.
Since when it comes to burning the temperature of the vegetation and that of the air are very important, people who have the responsibility to ignite fires should do it when the air and vegetation temperatures cannot encourage fires that can have adverse effects on the environment. For instance, prescribed fires in the United States during winter top kill the hard woods while hardwood rootstocks are killed by summer burns. In areas where burning has not been done for a longtime, deep organic layer that accumulates during prescribed burning leads to the cambial damage of trees.
Because only little heat is required to destroy the plant cells in growing plants, burning the vegetation kills growing plants. This leads to the short and long term destruction of the vegetation which over time exposes land to changes that impact negatively on the good conditions of the environment.
One short term and long term impact of prescribed burning in the Sequoia and Kings Canyon National parks in the United States is the change in species composition (Mary Berth, 2000). This change alters proper functioning of the ecosystem since it leads to the growth of new species while those that earlier existed and are not tolerant to fire before the fire fail to regenerate.
These two parks are located in California’s South Nevada areas. The parks cover about 864, 383 acres of land and prescribed burning in these two parks was made necessary by the desire to initiate ecological benefits in the parks. The two parks prescribed fire programs were developed in 1969 and continues to be implemented in order to reduce fuel hazard problem that may result from heavy surface fuel loads. Though the fires have been used to reduce the damage that may result from severe wild fires, change in species composition due to the clearing of land by fires has over the years been witnessed in the parks.
Fires have limited the growth of species that are not tolerant to the fire ignited over a long time. For instance, the increase in relative density of the giant Sequoia due to prescribed fires over a long time has altered the growth and survival of some other plant species. The successful fire regimes restoration in the parks has encouraged the regeneration of the species that are fire-adapted at the expense of the species that are less-adapted to fire. The reduction of fuel load and the restoration of forest structure after the fires alter the number and pattern of growth of plant species. The parks have conifer forests dominated by the sequoia species.
The change in the species number in a forest ecosystem affects the proper functioning of the natural ecosystem and this may lead to bare ground and soil erosion when plants and animals that promote proper functioning of the ecosystem are eliminated from the environment.
In ecologically sensitive habitats in the United States, prescribed fires have had adverse effects on the regeneration and survival of plant species. For example, the riparian areas in a forest system. A study carried out to determine the effect of prescribed fire on the riparian areas in the Dark Canyon area showed that the fire consumed 90 per cent of the ground fuel, 79 per cent of the riparian zone pre-fire fuel, and 34 per cent of the total surface fuel. The fire significantly reduced the percentage cover of the surface vegetation (Beche et al, 2005).
As compared to the unburned areas, the burned area showed a change in the plant taxa richness after the regeneration of vegetation. The reduction in plant taxa cover and richness changed the under story riparian vegetation community composition. These changes show that when an area experiences prescribed burning for a long time, disappearance of some species can lead to reduction in the percentage of vegetative cover.
In the California Oak woodlands, the Native Americans used fire to have the Oak woodland vegetation altered. Prescribed fires are considered to reduce the under story woody vegetation and have the tree density is lowered. After the fires, regeneration may result to growth of vegetation in patches. Since the settlement of Euro-Americans in the area, prescribed fire ignited in an ecosystem to create land for livestock ranches has removed the vegetation cover and instead encouraging the growth of plant species that are good for forage production.
The woody vegetation in the area has been affected.Eventually, reduced vegetation cover has made it easy for soil to be exposed to either wind or rain erosion.Prescribed fires in Oregon’s Mixed – conifer forests of Crater Lake over the years have altered species composition by killing species that are not fire resistant while providing favorable conditions for the regeneration of fire-resistant species (Agee, 2003). The Crater Lake National park has in the past prescribed a fire program that aims at increasing growth of pine trees and killing of the white fir tree species in the park. Natural ecosystems can undergo succession to form forests that are dominated by the hardwood.
The southeast region in the United States is considered to be the most fire dependent area in the country. The removal of fuel loads in burned areas impacts negatively on the environment when over time plant species that support proper functioning of an ecosystem are eliminated. This makes an ecosystem to be vulnerable to changes that have adverse effects on the environment.